Grid Application Programming Environments: Ibis, the GAT, and beyond

1
Grid Application Programming EnvironmentsIbis,
the GAT, and beyond

• Thilo Kielmann
• Vrije Universiteit, Amsterdam
• kielmann_at_cs.vu.nl

2
CoreGRID Network of Excellence

• Funded by European Commission (IST, 6th
  Framework)
• 8.2MEuro, for 4 years, started Sep 2004
• Goal integrating the research of the major
  European groups working on Grids
• Currently 42 partner sites
• 6 Virtual Institutes
• Knowledge and Data Management
• Programming Models (VUA)
• System Architecture
• Information and Monitoring Services
• Resource Management and Scheduling
• Systems, Tools, and Environments (VUA)

3
A Grid Application Execution Scenario
4
Functional Properties

• What applications need to do
• Access to compute resources, job spawning and
  scheduling
• Access to file and data resources
• Communication between parallel and distributed
  processes
• Application monitoring and steering

5
Non-functional Properties

• What else needs to be taken care of
• Performance
• Fault tolerance
• Security and trust
• Platform independence

6
Ibis
7
The Ibis System

• Java centric write once, run anywhere
• Efficient communication (pure Java or native)
• Programming models
• RMI (remote method invocation)
• GMI (group method invocation)
• Collective communication (MPI-like) and more
• RepMI (replicated method invocation)
• Strong consistency
• Satin (divide and conquer)
• MPJ (Java binding for MPI)

8
Satin Divide-and-conquer

• Effective paradigm for Grid applications
  (hierarchical)
• Satin Grid-friendly load balancing (aware of
  cluster hierarchy)
• Missing support for
• Fault tolerance
• Malleability
• Migration

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Satin Example Fibonacci
class Fib int fib (int n) if (n lt 2)
return n int x fib(n-1) int y
fib(n-2) return x y
Single-threaded Java
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Satin Example Fibonacci

• public interface FibInter extends
  ibis.satin.Spawnable
• public int fib (int n)
• class Fib extends ibis.satin.SatinObject
• implements FibInter
• public int fib (int n)
• if (n lt 2) return n
• int x fib(n-1) /spawned/
• int y fib(n-2) /spawned/
• sync()
• return x y

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Satin Grid-friendly load balancing (aware of
cluster hierarchy)

• Random Stealing (RS)
• Provably optimal on a single cluster (Cilk)
• Problems on multiple clusters
• (C-1)/C stealing over WAN
• Synchronous protocol
• Satin Cluster-aware Random Stealing (CRS)
• When idle
• Send asynchronous steal request to random node in
  different cluster
• In the meantime steal locally (synchronously)
• Only one wide-area steal request at a time

12
Satin Fault-tolerance, malleability, migration

• Can be implemented by handling processors joining
  or leaving the ongoing computation
• Processors may leave either unexpectedly (crash)
  or gracefully
• Handling joining processors is trivial
• Let them start stealing jobs
• Handling leaving processors is harder
• Recompute missing jobs
• Problems orphan jobs, partial results from
  gracefully leaving processors

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Summary Ibis

• Java-centric Grid programming environment
• Write once, run anywhere
• Efficient communication
• Satin Divide-and-Conquer
• CRS work stealing for clusters
• Fault tolerance integrated

14
The Grid Application Toolkit (GAT)
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Simple API for Grid Applications (SAGA)

• Follow-up to GAT efforts
• SAGA-RG within GGF is working on an upcoming
  standard for a simple Grid API
• 80 / 20 rule
• With 20 of the effort achieve 80 of the
  functionality
• Strictly driven by application use cases
• API defines large part of a Grid programming model

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What belongs to a Grid API?

• Functionality, e.g. (as in SAGA today)
• Jobs (submission and management)
• Files (and logical/replicated files)
• Streams
• Later in SAGA
• Steering, monitoring, workflow, GridRPC, GridCPR
• Security
• Error handling
• Asynchronous operation (-gt Tasks)

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SAGA Jobs

• interface Job
• void getJobId (out string
  jobId)
• void getJobState (out JobState
  state)
• void getJobInfo (out JobInfo
  info)
• void getJobDefinition (out JobDefinition
  jobDef)
• void getJobExitStatus (out JobExitStatus
  exitStatus)
• void suspend ()
• void resume ()
• void hold ()
• void release ()
• void checkpoint ()
• void migrate (in JobDefinition
  jobDef)
• void terminate ()
• void signal (in int
  signum)

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SAGA JobService

• interface JobService
• void submitJob (in JobDefinition
  jobDef,
• out Job
  job)
• void runJob (in string
  host,
• in string
  commandline,
• out opaque
  stdin,
• out opaque
  stdout,
• out opaque
  stderr,
• out Job
  job)
• void list (out arrayltstring,1gt
  jobIdList)
• void getJob (in string
  jobID,
• out Job
  job)

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SAGA Files

• class File
• void read (in long
  len_in,
• out string
  buffer,
• out long
  len_out )
• void write (in long
  len_in,
• in string
  buffer,
• out long
  len_out )
• void seek (in long
  offset,
• in SeekMode
  whence,
• out long
  position )
• void readV (inout arrayltivecgt
  ivec)
• void writeV (inout arrayltivecgt
  ivec)
• ...
• (directories left out for brevity)

20
SAGA Replicated Files

• class LogicalFile
• void addLocation (in name
  )
• void removeLocation (in name
  )
• void listLocations (out
  arrayltstring,1gt names )
• void replicate (in name
  )
• (directories left out for brevity)

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SAGA Security

• enum contextType
• X509 0,
• MyProxy 1,
• SSH 2
• Kerberos 3,
• UserPass 4
• interface Context extends-all SAGA.Attribute
• constructor (in contextType type)
• getType (out contextType type)
• Every SAGA object gets a Context as parameter to
  its constructor.

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SAGA Error Handling

• enum ExceptionCategory
• LibraryRecoverableError,
• LibraryFatalError,
• BackEndRecoverableError,
• BackEndFatalError,
• interface Exception extends sidl.SIDLException
• getExceptionCategory (out
  ExceptionCategory category)
• getMessage (out String
  message)
• interface ErrorHandler
• hasError (out boolean
  state)
• getErrorObject (out Exception
  error)
• Each SAGA object implements ErrorHandler.

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SAGA Tasks

• Asynchronous operations
• Bulk (async.) operations
• Single-threaded implementation support
• package Task
• enum State
• Pending 0,
• Running 1,
• Finished 2,
• Cancelled 3
• ...

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Tasks and Containers

• interface Task
• void run ()
• void wait (in double timeout,
• out boolean finished)
• void cancel ()
• void getState (out State state)
• class TaskContainer
• void addTask (in Task
  task)
• void removeTask (in Task
  task)
• void run ()
• void wait (in double
  timeout,
• out arrayltTask,1gt
  finished)
• void cancel ()
• void getStates (out arrayltState,1gt
  states)
• void listTasks (out arrayltTask,1gt
  tasks)

25
Instantiating Tasks

• Have three versions of each operation
• Synchronous
• Asynchronous (start immediately)
• Task (start explicitly)
• d.mkdir ("test/")
• sagatask t_1 d.mkdir_async ("test/")
• sagatask t_2 d.mkdir_task ("test/")
• t_2.run ()
• t_1.wait ()
• t_2.wait ()

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Summary SAGA

• Standardize a simple API for Grid applications
• Driven by user communities
• API completion Q1/2006
• First engine implementation in C
  (SAGA-A)almost complete

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Beyond Ibis and GAT/SAGASynthesizing a Generic
Architecture
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Beyond Ibis and GAT/SAGABuilding
Component-based Grid Systems
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Conclusions

• Ibis efficient communication for
  (Java-based)Grid applications
• GAT/SAGA Simple API to vaarious Grid systemsand
  middlewares
• Work in progress
• designing/building a generic grid platform
• www.coregrid.net
• www.cs.vu.nl/ibis
• wiki.cct.lsu.edu/saga/space/start

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Acknowledgements

• Ibis
• Henri Bal, Jason Maassen, Rob van
  Nieuwpoort,Gosia Wrzesinska, Ceriel Jacobs
• GAT / SAGA
• Rob van Nieuwpoort, Jason Maassen,Andre Merzky,
  Michel Zandstra, Stephan HirmerHartmut Kaiser,
  Shantenu Jha, Tom Goodale,...
• Funding
• European Commission (CoreGRID, GridLab)
• Dutch Ministry of Education, Culture, and Science
  (OCW) via www.vl-e.nl